JPH0636974A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain electrolyte for driving an electrolytic capacitor wherein withstand voltage is high, life characteristic and low temperature characteristics are excellent, and stable characteristics under applied voltage are obtained. CONSTITUTION:In the solvent composed of 98ml alpha-butyrolactone and 2ml ethylene glycol, the following are dissolved as solute; 10g triethylmethyl sebacate ammonium salt and 1g boric acid. By using the above electrolyte, an electrolytic capacitor whose rating is 100V-220muF is manufactured for experiment, and subjected to a high temperature load test at 105 deg.C for 2000 hours. The result shows that change amount of tandelta, change amount of leak current, and capacitance change ratio are low as compared with electrolytic capacitors using the conventional electrolyte.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution for driving an electrolytic capacitor.

[0002]

2. Description of the Related Art In an electrolytic capacitor, a capacitor element formed by winding separator paper impregnated with a driving electrolytic solution (hereinafter referred to as electrolytic solution) together with an aluminum foil is housed in an aluminum or synthetic resin case and hermetically sealed. It has a structure.

In the electrolytic solution of such an electrolytic capacitor,
Using ethylene glycol as the main solvent, adipic acid, formic acid,
An organic acid such as benzoic acid or a salt thereof, or an inorganic acid such as boric acid or phosphoric acid or a salt thereof is often used as a solute.

In recent years, an electrolytic solution having excellent characteristics such as withstand voltage and thermal stability has been demanded. As an electrolytic solution having high electric conductivity and excellent thermal stability, γ-butyrolactone is used as a solvent and phthalic acid is used. An electrolytic solution in which a tetramethylammonium phthalate, which is a quaternary ammonium salt, is dissolved as a solute has been proposed (Japanese Patent Laid-Open No. 63-69213).

This electrolytic solution has high conductivity and excellent life characteristics, and has a solvent of γ-butyrolactone (melting point-43.53).
(° C) is used, so it has excellent low temperature characteristics. However, this electrolytic solution has a low withstand voltage, and the rated voltage of the electrolytic capacitor using this electrolytic solution is limited to 35 to 50V.

[0006]

Further, an electrolytic solution in which γ-butyrolactone is used as a solvent and a quaternary ammonium salt of sebacic acid is dissolved as a solute has been proposed (JP-A-62-62).
No. 248217). An electrolytic capacitor using this electrolytic solution has excellent thermal stability and life characteristics and high withstand voltage. However, in this electrolytic capacitor, the oxide film formed on the anode is easily destroyed when a voltage is applied,
Therefore, the withstand voltage sharply decreases. From this, there is a problem that this electrolytic solution makes the characteristics unstable when a voltage is applied to the electrolytic capacitor.

The present invention has been made in view of the above circumstances, and is an electrolytic solution for driving an electrolytic capacitor having high withstand voltage, excellent life characteristics and low temperature characteristics, and stable characteristics when a voltage is applied. The purpose is to provide.

[0008]

An electrolytic solution for driving an electrolytic capacitor according to a first aspect of the present invention is an electrolytic solution for driving an electrolytic capacitor, which comprises γ-butyrolactone as a main solvent and a quaternary ammonium salt of sebacic acid as a main solute. In (1), boric acid and ethylene glycol are dissolved.

The electrolytic solution for driving an electrolytic capacitor according to the second aspect of the present invention is an electrolytic solution for driving an electrolytic capacitor, which comprises γ-butyrolactone as a main solvent and a quaternary ammonium salt of sebacic acid as a main solute. On the other hand, it is characterized in that boric acid having a content of 0.5 to 2 g and ethylene glycol having a content of 1 to 5 ml are dissolved.

[0010]

FIG. 1 is a graph showing the voltage rising characteristic of the electrolytic solution. The vertical axis represents voltage and the horizontal axis represents time. Figure 1 (a)
Shows a voltage rise characteristic obtained by mounting an electrode on an electrolyte solution prepared by dissolving 10 g of conventional γ-butyrolactone as a solvent and 10 g of triethylmethylammonium sebacate salt as a solute, and measuring the voltage applied thereto. When the voltage is gradually increased, the voltage applied to this electrolyte is 200
After rising to V, it drops sharply. It is considered that this is because the oxide film formed on the aluminum surface which is the positive electrode was destroyed by applying a high voltage, and the withstand voltage of this electrolytic solution was lowered.

On the other hand, FIG. 1 (b) shows γ-butyrolactone 98.
Electrodes were attached to an electrolyte solution in which 10 ml of triethylmethylammonium sebacate and 1 g of boric acid were dissolved as a solute using 2 ml of ethylene glycol and 2 ml of ethylene glycol as a solvent, and the voltage applied to this electrode was measured. In this electrolytic solution, when the voltage is gradually increased, the voltage applied reaches a peak of about 190V, maintains 190V, and does not drop. From this, it can be said that the inclusion of boric acid and ethylene glycol for dissolving the boric acid suppresses the destruction of the oxide film due to the application of a high voltage.

In the electrolytic solution for driving an electrolytic capacitor of the present invention, γ-butyrolactone is used as a main solvent and the quaternary ammonium salt of sebacic acid is used as a main solute. The electrolytic solution for driving an electrolytic capacitor contains boric acid and ethylene glycol. Let At this time, boric acid is dissolved in ethylene glycol and mixed with γ-butyrolactone. As a result, an electrolytic capacitor using this electrolytic solution has a high withstand voltage, excellent life characteristics and low temperature characteristics, and exhibits stable characteristics when a voltage is applied. The contents of these are 0.5 to 2 g of boric acid and 1 of ethylene glycol with respect to 100 ml of the solvent.
A superior effect is exhibited when the amount is ~ 5 ml.

[0013]

EXAMPLES Examples of the present invention will be specifically described below along with conventional examples.

[0014]

[Table 1]

Table 1 is a table showing the solvents and solutes of the electrolytic solutions A, B, C, D, E and F. Electrolyte solutions A, B, and C of Examples were prepared by dissolving γ-butyrolactone and ethylene glycol as solvents and using triethylmethylammonium sebacate and boric acid as solutes. Electrolyte solutions A, B, and C have different mixture ratios of solvent and solute, respectively. Electrolyte solution A contains γ-butyrolactone and ethylene glycol in a solvent of 95: 5 (%),
10 g of triethylmethylammonium sebacate salt and 2 g of boric acid were dissolved in 100 ml, and the electrolytic solution B contained γ-butyrolactone and ethylene glycol at 98: 2 (%).
Solvent of triethylmethylammonium sebacate
10 g, 1 g of boric acid dissolved, electrolyte B is γ-butyrolactone and ethylene glycol 99: 1 (%) in a solvent of 10 g of tetramethylammonium sebacate and 0.5 g of boric acid.
It is melted. Here, boric acid is dissolved in ethylene glycol and mixed with γ-butyrolactone.

The electrolytic solutions D, E and F are conventional examples, and the electrolytic solution D is a solution in which 100 ml of γ-butyrolactone is used as a solvent and 20 g of tetramethylammonium phthalate salt is dissolved as a solute, and the electrolytic solution E is γ-. Sebacic acid triethylmethyl ammonium salt with 100 ml of butyrolactone as solvent
Even if 10g is dissolved, the electrolyte F is ethylene glycol 10
It was prepared by dissolving 10 g of ammonium adipate in 0 ml of a solvent.

Electrodes were attached to these electrolytes A, B, C, D, E, F, and the results of measuring the electric conductivity and withstand voltage, and the electrolytes A, B, C, D, E, F Electrolytic capacitor (rated 100V-220μF, external dimensions φ16mm × 25
mm) was prototyped and the condition when aged at 85 ° C and 100V is shown in Table 2.

[0018]

[Table 2]

As shown in Table 2, the electrolytic solution D of the conventional example has a low withstand voltage, and when an electrolytic capacitor using this was aged at 100 V for 1 hour at 85 ° C., a voltage higher than the withstand voltage was applied. As a result, a short circuit occurs in which the anode and the cathode of the electrolytic capacitor come into contact with each other, causing a large number of punctures (hereinafter referred to as short puncture), which makes aging impossible.

Twenty of each of these electrolytic capacitors were prototyped and subjected to a high temperature load test (rated voltage continuous application test) at 105 ° C. for 2000 hours. Capacity change rate after 2000 hours (ΔC
/ C), measured values of loss (tan δ) which is an index of electric resistance and leakage current, and initial values of capacity, tan δ and leakage current are shown in Table 3.

[0021]

[Table 3]

As shown in Table 3, it can be seen that the electrolytic capacitor using the electrolytic solution F of the conventional example has a high rate of change in capacitance and tan δ, and has poor life characteristics. Further, in the electrolytic capacitors using the electrolytic solution E of the conventional example, two short punctures occurred during the high temperature load test. It is considered that this is because the oxide film of the electrolytic capacitor is destroyed during the high temperature load test for a long time, causing a rapid change in the withstand voltage.

In comparison with these, the electrolytic solution A of this embodiment,
It can be seen that the electrolytic capacitors using B and C have a low capacity change rate, tan δ and leakage current value, do not cause short puncture, and show stable characteristics.

Further, as shown in Table 2, the electrolytic solutions A, B,
The conductivity of C decreases as the amount of boric acid and ethylene glycol added increases, and as shown in Table 3, the electrolyte solution E to which boric acid is not added causes short puncture, and the amount of boric acid added. As the amount of boric acid becomes difficult to dissolve in the solvent, the amount of boric acid added is 0.5g to 2g.
Can be said to be an appropriate amount. The appropriate amount of ethylene glycol for dissolving this amount of boric acid is 1 ml to 5 ml.

[0025]

As described above, the electrolytic solution for driving the electrolytic capacitor of the present invention contains γ-butyrolactone as the main solvent,
By adding boric acid and ethylene glycol to the electrolytic solution containing quaternary ammonium salt of sebacic acid as the main solute, high withstand voltage, excellent life characteristics and low temperature characteristics, and stable characteristics when high voltage is applied are obtained. An electrolytic capacitor having the same can be obtained, and the present invention has excellent effects.

[Brief description of drawings]

FIG. 1 is a graph showing a voltage rising characteristic of an electrolytic solution.

Claims (2)

[Claims] 1. An electrolytic capacitor, characterized in that boric acid and ethylene glycol are dissolved in an electrolytic solution for driving an electrolytic capacitor containing γ-butyrolactone as a main solvent and a quaternary ammonium salt of sebacic acid as a main solute. Electrolyte for driving. 2. The electrolytic capacitor driving apparatus according to claim 1, wherein the content of the boric acid is 0.5 to 2 g and the content of the ethylene glycol is 1 to 5 ml with respect to 100 ml of the solvent. Electrolyte.